Soccer America continues its examination of the favorites with a look at the USA, which heads into the 2007 Women's World Cup as the odds-on favorite.

After all, they are undefeated in their last 47 games and have yet to lose under their rigorous coach, Greg Ryan.

The U.S. women believe they may be the best women's team ever assembled.

They are surely "The Greatest Team You've Never Heard Of," as they have been billed by team sponsor Nike.

They take to the field for the first time on Tuesday when they face North Korea in Chengdu (TV: ESPN2, live, 4:55 am ET).

Here are five reasons why the USA will win the Womens World Cup.1. KRISTINE LILLY. The sole survivor from the 1991 U.S. world championship team, Kristine Lilly is at 36 playing the best soccer of her career.

She played much of her career in midfield but now patrols the left side of the U.S. attack with great effect. The world recordholder with 331 caps has nine goals and five assists in 12 games in 2007.

This will be her fifth and last World Cup. She hopes to start a family soon and says she has no intention of playing again after becoming a mother.

2. ABBY WAMBACH. Abby Wambach (77 goals in 96 games) has a better strike rate than other U.S. greats like Mia Hamm (158 goals in 275 games) and Michelle Akers (105 goals in 136 games). Wambach, who has scored a a team-leading 11 goals in 2007, left the final World Cup tuneup against Finland in the 27th minute with a toe injury but sustained no serious damage.

"Abby's tough enough that some minor pain is not going to stop her," said Ryan. "She's just an awfully tough person. In the CONCACAF qualifying tournament, she was on a bad ankle that entire Gold Cup, and she scored the goals to get us into the World Cup, so Abby will be fine."

3. DEPTH. Ryan says a big difference from the past is that the USA no longer rely on a few players.

Nowhere is the U.S. depth more evident than in midfield.

Shannon Boxx, arguably the best holding midfielder in women's soccer, was out for eight months with a knee injury, and Leslie Osborne stepped in and played very well.

Carli Lloyd, who scored one goal for the USA going into 2007, scored goals in all four games at the 2007 Algarve Cup, where she was named the best player, and is another key player.

Aly Wagner, one of the best playmakers in women's soccer, would start on most other teams, but she is a role player on the U.S. national team.

4. YOUTH. Veteran Heather Mitts went down with a knee injury, and Stephanie Lopez, a senior at the University of Portland, has stepped into the starting lineup.

Lopez is one of five possible starters who have not played in a World Cup. The others are goalkeeper Hope Solo, midfielder Lori Chalupny, forward Lindsay Tarpley and Lloyd.

Heather O'Reilly and Marian Dalmy were still playing college ball last season, while Tarpley and Chalupny, O'Reilly's former North Carolina teammates, are only two years removed from college soccer.

5. VERSATILITY. Lopez, a left back for most of her young international career, has also been used in midfield as Ryan has experimented with a 3-4-3 formation in place of his usual 4-3-3.

"We wanted to make sure we know how to play in as many systems as possible with as many different combinations of players as possible," says Ryan. "And so I feel good that there are four or five systems we could use in this World Cup, if we need to."